Method of manufacturing a semiconductor device

ABSTRACT

A method of manufacturing a semiconductor device includes forming a first layer including an organic material over a substrate. A second layer including a reaction product of a silicon-containing material and a photoacid generator is formed over the first layer. A photosensitive layer is formed over the second layer, and the second layer is patterned.

BACKGROUND

As consumer devices have gotten smaller and smaller in response toconsumer demand, the individual components of these devices havenecessarily decreased in size as well. Semiconductor devices, which makeup a major component of devices such as mobile phones, computer tablets,and the like, have been pressured to become smaller and smaller, with acorresponding pressure on the individual devices (e.g., transistors,resistors, capacitors, etc.) within the semiconductor devices to also bereduced in size.

One enabling technology that is used in the manufacturing processes ofsemiconductor devices is the use of photolithographic materials. Suchmaterials are applied to a surface of a layer to be patterned and thenexposed to an energy that has itself been patterned. Such an exposuremodifies the chemical and physical properties of the exposed regions ofthe photosensitive material. This modification, along with the lack ofmodification in regions of the photosensitive material that were notexposed, can be exploited to remove one region without removing theother.

However, as the size of individual devices has decreased, processwindows for photolithographic processing has become tighter and tighter.As such, advances in the field of photolithographic processing arenecessary to maintain the ability to scale down the devices, and furtherimprovements are needed in order to meet the desired design criteriasuch that the march towards smaller and smaller components may bemaintained.

BRIEF DESCRIPTION OF THE DRAWINGS

The present disclosure is best understood from the following detaileddescription when read with the accompanying figures. It is emphasizedthat, in accordance with the standard practice in the industry, variousfeatures are not drawn to scale and are used for illustration purposesonly. In fact, the dimensions of the various features may be arbitrarilyincreased or reduced for clarity of discussion.

FIG. 1 illustrates a process flow of manufacturing a semiconductordevice according to embodiments of the disclosure.

FIG. 2 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 3 shows a process stage of a sequential operation according toembodiments of the disclosure.

FIG. 4 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIGS. 5A and 5B show a process stage of a sequential operation accordingto an embodiment of the disclosure.

FIG. 6 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 7 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 8 shows a process stage of a sequential operation according to anembodiment of the disclosure.

FIG. 9 shows a process stage of sequential operations according to anembodiment of the disclosure.

FIGS. 10A, 10B, 10C, and 10D show process stages of sequentialoperations according to an embodiment of the disclosure.

FIG. 11 illustrates polymers for bottom layer compositions according toembodiments of the disclosure.

FIG. 12 illustrates polymers for bottom layer compositions according toembodiments of the disclosure.

FIG. 13 illustrates polymers for bottom layer compositions according toembodiments of the disclosure.

FIGS. 14A, 14B, and 14C illustrate polymers for bottom layercompositions according to embodiments of the disclosure.

FIGS. 15A and 15B illustrate polymerization reactions of components ofthe middle layer according to embodiments of the disclosure.

FIGS. 16A and 16B illustrate photoacid generator monomer units accordingto embodiments of the disclosure.

FIG. 17 illustrates the acid generation reaction of polymer boundphotoacid generators according to an embodiment of the disclosure.

FIG. 18 shows a semiconductor device manufactured by a method accordingto an embodiment of the disclosure.

FIGS. 19A, 19B, 19C, 19D, 19E, 19F, 19G, 19H, 19I, 19J, 19K, 19L, 19M,19N, 19O, 19P, 19Q, and 19R show a sequential operation according toembodiments of the disclosure.

DETAILED DESCRIPTION

It is to be understood that the following disclosure provides manydifferent embodiments, or examples, for implementing different featuresof the disclosure. Specific embodiments or examples of components andarrangements are described below to simplify the present disclosure.These are, of course, merely examples and are not intended to belimiting. For example, dimensions of elements are not limited to thedisclosed range or values, but may depend upon process conditions and/ordesired properties of the device. Moreover, the formation of a firstfeature over or on a second feature in the description that follows mayinclude embodiments in which the first and second features are formed indirect contact, and may also include embodiments in which additionalfeatures may be formed interposing the first and second features, suchthat the first and second features may not be in direct contact. Variousfeatures may be arbitrarily drawn in different scales for simplicity andclarity.

Further, spatially relative terms, such as “beneath,” “below,” “lower,”“above,” “upper” and the like, may be used herein for ease ofdescription to describe one element or feature's relationship to anotherelement(s) or feature(s) as illustrated in the figures. The spatiallyrelative terms are intended to encompass different orientations of thedevice in use or operation in addition to the orientation depicted inthe figures. The device may be otherwise oriented (rotated 90 degrees orat other orientations) and the spatially relative descriptors usedherein may likewise be interpreted accordingly. In addition, the term“made of” may mean either “comprising” or “consisting of.”

As semiconductor device pattern features become smaller, photoresistpattern resolution becomes more important. Extreme ultraviolet (EUV)lithography technology is used as pattern sizes become smaller due tobetter resolution than immersion ArF lithography. However, scum defectsmay be formed during EUV lithography because of weak absorption of thephotoresist by 13.5 nm radiation. Undeveloped resist remaining intrenches could lead to bridging lines or footing, resulting in failureof transferring the photoresist pattern to underlying layers.

Trilayer resists are used to provide increased pattern resolution andetching electivity. Trilayer resists include a bottom layer, middlelayer, and an upper, photosensitive layer. A high Si content middlelayer provides good adhesion, low reflectivity, and a high degree ofetching selectivity to both the photosensitive upper layer and thebottom layer. In some embodiments, middle layer monomers cross-link whenheated, and terminal hydroxyl groups react with Si—O bonds to form highmolecular weight polymers. The bottom layer, such as a bottomanti-reflective coating (BARC) or spin on carbon (SOC) coating, is usedto planarize the device or protect semiconductor device features, suchas the metal gates, during subsequent processing operations. Embodimentsof the present disclosure include methods and materials that reduce scumdefects, thereby improving pattern resolution, decreasing line widthroughness, decreasing line edge roughness, and improving semiconductordevice yield. Embodiments of the disclosure further enables the use oflower exposure doses to effectively expose and pattern the photoresist.

Embodiments of the disclosure include a polymer bound photoacidgenerator (PAG) in the middle layer. In some embodiments, the PAG is acationic onium group. Upon exposure to actinic radiation the PAGgenerates an acid in the middle layer, and generated acid subsequentlydiffuses from the middle layer across the middle layer/upper layerinterface in the exposure area. The acid diffusing into the upper,photosensitive layer reacts with the resist polymer and reduces the scumdefect. In addition, the acid diffusing from the middle layersupplements photogenerated acid in the upper layer, thereby reducing theexposure dose necessary to fully expose the photosensitive layer. Lowerrequired exposure doses increases the number of wafers per hour (WPH)than can be processed during the lithography operation, resulting inhigher device yield and increased device manufacturing efficiency.

FIG. 1 illustrates a process flow 100 of manufacturing a semiconductordevice according to embodiments of the disclosure. A first layer (orbottom layer) composition is coated over the surface of a substrate inoperation S105 to form a first (or bottom) layer 110, as shown in FIG. 2. In some embodiments, the substrate has device features formed thereon,as shown in FIG. 2 . In some embodiments, the bottom layer 110 is abottom anti-reflection coating (BARC) layer or a planarizing layer. Insome embodiments, the bottom layer 110 is a spin-on carbon layer. Insome embodiments, the bottom layer 110 has a thickness ranging fromabout 10 nm to about 2,000 nm. In some embodiments, the thickness of thebottom layer ranges from about 200 nm to about 1,500 nm. Bottom layerthicknesses less than the disclosed ranges may not provide sufficientprotection to the semiconductor device features from subsequentprocessing operations or sufficient planarization. Bottom layerthicknesses greater than the disclosed ranges may be unnecessarily thickand may not provide any additional significant protection of underlyingdevice features or planarization. In some embodiments, the underlyingfeatures include transistors having fin structures or gate structures.In some embodiments, the underlying features include a conductive layer105, such as a metal layer.

The bottom layer 110 undergoes a first baking operation S110 toevaporate solvents or cure the bottom layer composition in someembodiments. In some embodiments, the baking operation S110 crosslinksthe bottom layer composition. The bottom layer 110 is baked at atemperature and time sufficient to cure and dry the bottom layer 110. Insome embodiments, the bottom layer is heated at a temperature rangingfrom about 40° C. to about 400° C. for about 10 seconds to about 10minutes. In other embodiments, the bottom layer 110 is heated at atemperature ranging from about 100° C. to about 400° C. In otherembodiments, the bottom layer 110 is heated at a temperature rangingfrom about 250° C. to about 350° C. In other embodiments, the bottomlayer 110 is heated at a temperature ranging from about 200° C. to about300° C. Heating the bottom layer at temperatures below the disclosedranges may result in insufficient curing or crosslinking, while heatingthe bottom layer at temperatures greater than the disclosed ranges mayresult in damage to the bottom layer and the underlying device features.In some embodiments, the curing operation S110 is performed by exposingthe bottom layer to actinic radiation. In some embodiments, the actinicradiation is ultraviolet radiation. In some embodiments, the ultravioletradiation has a wavelength ranging from about 100 nm to less than about300 nm.

In some embodiments, capillary force between the bottom layercomposition and the substrate 10 or conductive layer 105 enhances thegap filling of the bottom layer composition. Polar groups in polymers inthe bottom layer composition may interact with the conductive layer 105or the substrate 10, which may enhance the gap filling.

A second layer (or middle layer) composition is coated over the surfaceof the bottom layer 110 in operation S115 to form a second (or middle)layer 115, as shown in FIG. 3 . The middle layer 115 may have acomposition that provides anti-reflective properties for thephotolithography operation or hard mask properties. In some embodiments,the middle layer 115 has high etching selectivity relative to both thebottom layer and the upper layer, and the middle layer 115 provides goodadhesion to both the bottom layer and the upper layer. In someembodiments, the middle layer 115 includes a silicon-containing layer(e.g., a silicon hard mask material). The middle layer 115 may include asilicon-containing inorganic polymer. In some embodiments, the middlelayer composition includes silicon-containing monomers, photoacidgenerators, silicon-containing monomers with bound photoacid generatorgroups or combinations thereof.

In some embodiments, the middle layer 115 has a thickness ranging fromabout 10 nm to about 500 nm. In some embodiments, the thickness of themiddle layer 115 ranges from about 20 nm to about 200 nm. In someembodiments, a ratio of the bottom layer thickness to the middlethickness ranges from about 1:1 to about 200:1. Middle layer thicknessesless than the disclosed ranges may not provide sufficient adhesion oretching resistance. Middle layer thicknesses greater than the disclosedranges may be unnecessarily thick and may not provide any additionalsignificant adhesion or etching resistance.

The middle layer 115 undergoes a second baking operation S120 toevaporate solvents or cure the middle layer composition in someembodiments. In some embodiments, the second baking operation S120causes a compound having a photoacid generator group andsilicon-containing compound to react. In some embodiments, the secondbaking operation S120 causes a monomer having a photoacid generatorgroup and a silicon-containing monomer to polymerize or crosslink. Themiddle layer 115 is heated at a temperature ranging from about 150° C.to about 300° C. for about 10 seconds to about 10 minutes. In otherembodiments, the middle layer 115 is heated at a temperature rangingfrom about 200° C. to about 250° C. Heating the middle layer attemperatures below the disclosed ranges may result in insufficientcuring or crosslinking, while heating the bottom layer at temperaturesgreater than the disclosed ranges may result in damage to the middlelayer and the underlying device features.

A photosensitive upper layer 120 is formed by coating a resistcomposition over the middle layer 115 in operation S125, as shown inFIG. 4 in some embodiments. In some embodiments, the photosensitivelayer 120 is a photoresist layer. Together, the bottom layer 110, middlelayer 115, and the photosensitive (or upper) layer 120 make up atrilayer resist 125. Then, the photoresist layer 120 undergoes a thirdbaking operation S130 (or pre-exposure baking) to evaporate solvents inthe resist composition in some embodiments. The photosensitive layer 120is baked at a temperature and time sufficient to cure and dry thephotosensitive layer 120. In some embodiments, the photosensitive layeris heated at a temperature of ranging from about 40° C. to about 120° C.for about 10 seconds to about 10 minutes.

After the pre-exposure baking operation S130 of the photoresist layer120, the photoresist layer 120 and the middle layer 115 are selectivelyexposed (or patternwise exposed) to actinic radiation 45/97 (see FIGS.5A and 5B) in operation S135. In some embodiments, the photoresist layer120 and middle layer are selectively exposed to ultraviolet radiation.In some embodiments, the radiation is electromagnetic radiation, such asg-line (wavelength of about 436 nm), i-line (wavelength of about 365nm), ultraviolet radiation, deep ultraviolet radiation, extremeultraviolet, electron beams, or the like. In some embodiments, theradiation source is selected from the group consisting of a mercuryvapor lamp, xenon lamp, carbon arc lamp, a KrF excimer laser light(wavelength of 248 nm), an ArF excimer laser light (wavelength of 193nm), an F₂ excimer laser light (wavelength of 157 nm), or a CO₂laser-excited Sn plasma (extreme ultraviolet, wavelength of 13.5 nm).

As shown in FIG. 5A, the exposure radiation 45 passes through aphotomask 30 before irradiating the photoresist layer 120 and middlelayer 115 in some embodiments. In some embodiments, the photomask 30 hasa pattern to be replicated in the photoresist layer 120. The pattern isformed by an opaque pattern 35 on the photomask substrate 40, in someembodiments. The opaque pattern 35 may be formed by a material opaque toultraviolet radiation, such as chromium, while the photomask substrate40 is formed of a material that is transparent to ultraviolet radiation,such as fused quartz.

In some embodiments, the selective exposure of the photoresist layer 120and middle layer 115 to form exposed regions 50, 115 a and unexposedregions 52, 115 is performed using extreme ultraviolet lithography. Inan extreme ultraviolet lithography operation, a reflective photomask 65is used to form the patterned exposure light in some embodiments, asshown in FIG. 5B. The reflective photomask 65 includes a low thermalexpansion glass substrate 70, on which a reflective multilayer 75 of Siand Mo is formed. A capping layer 80 and absorber layer 85 are formed onthe reflective multilayer 75. A rear conductive layer 90 is formed onthe back side of the low thermal expansion glass substrate 70. Inextreme ultraviolet lithography, extreme ultraviolet radiation 95 isdirected towards the reflective photomask 65 at an incident angle ofabout 6°. A portion 97 of the extreme ultraviolet radiation is reflectedby the Si/Mo multilayer 75 towards the photoresist coated substrate 10,while the portion of the extreme ultraviolet radiation incident upon theabsorber layer 85 is absorbed by the photomask. In some embodiments,additional optics, including mirrors, are between the reflectivephotomask 65 and the photoresist coated substrate.

The region 50 of the photoresist layer exposed to radiation undergoes achemical reaction thereby changing its solubility in a subsequentlyapplied developer relative to the region of the photoresist layer notexposed to radiation 52. In some embodiments, the actinic radiationcauses a photoacid generator in the portions of the middle layer 115exposed to radiation to generate an acid. In some embodiments, theactinic radiation causes a photoacid generator in the photoresist layer120 to generate an acid. In some embodiments, an anion or a cation of aphotoacid generator compound in the photoresist layer 120 and isdifferent from an anion or a cation of a photoacid generator in themiddle layer 115.

Next, the trilayer resist 125 undergoes a fourth baking (orpost-exposure bake (PEB)) in operation S140. In some embodiments, thephotosensitive layer 120 and the middle layer 115 are heated at atemperature ranging from about 50° C. to about 160° C. for about 20seconds to about 120 seconds. The post-exposure baking may be used toassist in the generating, dispersing, and reacting of the acid generatedfrom the impingement of the radiation 45/97 upon the photoresist layer120 and middle layer 115 during the exposure. The post-exposure bakingoperation S140 assists acid generated in the middle layer 115 a todiffuse from portions 115 a of the middle layer exposed to the actinicradiation into the exposed portions 50 of the photoresist layer 120.Such assistance helps to create or enhance chemical reactions, whichgenerate chemical differences between the exposed region 50 and theunexposed region 52 within the photoresist layer, thereby improving theresolution of the subsequently developed pattern and reducing resistscum which may otherwise occurs at the bottom of the photoresist layer120.

The selectively exposed photoresist layer is subsequently developed byapplying a developer to the selectively exposed photoresist layer inoperation S145. As shown in FIG. 6 , a developer 57 is supplied from adispenser 62 to the selectively exposed photoresist layer 120. In someembodiments, the exposed region 50 of the photoresist layer is removedby the developer 57 forming a pattern of openings 55 in the photoresistlayer 120 to expose the middle layer 115 a, as shown in FIG. 7 .

In some embodiments, the openings or pattern 55 in the photoresist layerare extended through the middle layer 115 and the bottom layer 110 inoperation S150 using suitable etchants selective to each respectivelayer to form an extended opening or pattern 55′, as shown in FIG. 8 .

In some embodiments, an exposed portion of underlying layers, such asthe conductive layer 105 in the extended opening or pattern 55′ isremoved using a suitable etching operation, as shown in FIG. 8 . Thephotoresist layer 120, middle layer 115, and bottom layer 110 aresubsequently removed in operation S155 using suitable photoresiststripping, etching, or plasma ashing operations, as shown in FIG. 9 . Inother embodiments, after the pattern 55 of the photoresist layer 120 isextended to the middle layer 115 to form a patterned middle layer, thephotoresist layer 120 is removed, and then by using the patterned middlelayer as an etching mask, the bottom layer 110 (and the conductive layer105) is patterned.

In other embodiments, an interlayer dielectric (ILD) layer 145 is formedover the features disposed over the substrate 10, as shown in FIG. 10A.A trilayer resist 125 is formed, using the materials and operationsdescribed herein, over the ILD layer 145, and an opening 140 is formedin the trilayer resist 125. The photoresist layer 120 is removed by asuitable photoresist stripping or plasma ashing operation, as shown inFIG. 10B in some embodiments. Then the middle layer 115 is used as ahard mask to extend the opening 140 into the ILD layer 145 forming a via140′ exposing the conductive layer 105. After forming the via 140′, themiddle layer and bottom layer are removed by suitable operations, suchas etching and plasma ashing, as shown in FIG. 10C. A conductive contact150 is subsequently formed connected to the conductive layer 105 byfilling the via 140′ with a conductive material by a suitable depositiontechnique, as shown in FIG. 10D. In some embodiments, the depositiontechniques include chemical vapor deposition (CVD), physical vapordeposition (PVD), or atomic layer deposition (ALD) techniques. In someembodiments, the conductive contact 150 is formed of one or more metalsselected from tungsten, copper, nickel, titanium, tantalum, aluminum,and alloys thereof. In some embodiments, a planarizing operation, suchas chemical-mechanical polishing or an etch back operation is performedto remove metal deposited over the upper surface of the ILD layer 145.

In some embodiments, the substrate 10 includes a single crystallinesemiconductor layer on at least it surface portion. The substrate 10 mayinclude a single crystalline semiconductor material such as, but notlimited to Si, Ge, SiGe, GaAs, InSb, GaP, GaSb, InAlAs, InGaAs, GaSbP,GaAsSb and InP. In some embodiments, the substrate 10 is a silicon layerof an SOI (silicon-on insulator) substrate. In certain embodiments, thesubstrate 10 is made of crystalline Si.

The substrate 10 may include in its surface region, one or more bufferlayers (not shown). The buffer layers can serve to gradually change thelattice constant from that of the substrate to that of subsequentlyformed source/drain regions. The buffer layers may be formed fromepitaxially grown single crystalline semiconductor materials such as,but not limited to Si, Ge, GeSn, SiGe, GaAs, InSb, GaP, GaSb, InAlAs,InGaAs, GaSbP, GaAsSb, GaN, GaP, and InP. In an embodiment, the silicongermanium (SiGe) buffer layer is epitaxially grown on the siliconsubstrate 10. The germanium concentration of the SiGe buffer layers mayincrease from 30 atomic % for the bottom-most buffer layer to 70 atomic% for the top-most buffer layer.

In some embodiments, the substrate 10 includes one or more layers of atleast one metal, metal alloy, and metal nitride/sulfide/oxide/silicidehaving the formula MX_(a), where M is a metal and X is N, S, Se, O, Si,and a is from about 0.4 to about 2.5. In some embodiments, the substrate10 includes titanium, aluminum, cobalt, ruthenium, titanium nitride,tungsten nitride, tantalum nitride, and combinations thereof.

In some embodiments, the substrate 10 includes a dielectric having atleast a silicon or metal oxide or nitride of the formula MX_(b), where Mis a metal or Si, X is N or O, and b ranges from about 0.4 to about 2.5.In some embodiments, the substrate 10 includes silicon dioxide, siliconnitride, aluminum oxide, hafnium oxide, lanthanum oxide, andcombinations thereof.

FIG. 11 illustrates some components of the bottom layer, BARC,planarizing layer, or spin-on carbon layer (the bottom layer)composition according to some embodiments of the disclosure. In someembodiments, the bottom layer composition includes an organic polymer,including, but not limited to polyhydroxystyrenes, polyacrylates,polymethacrylates, polyvinylphenols, polystyrenes, and copolymersthereof. In some embodiments, the organic polymer is apoly(4-hydroxystyrene), a poly(4-vinylphenol-co-methyl methacrylate)copolymer, and a poly(styrene)-b-poly(4-hydroxystyrene) copolymer, asillustrated in FIG. 11 .

In some embodiments, the bottom layer composition includes a carbonbackbone polymer, a first crosslinker, and a second crosslinker.

In some embodiments, the first crosslinker is one or more selected fromthe group consisting of A-(OR)_(x), A-(NR)_(x),

where A is a monomer, oligomer, or a second polymer having a molecularweight ranging from about 100 to about 20,000; R is an alkyl group,cycloalkyl group, cycloalkylepoxy group, or C3-C15 heterocyclic group;OR is an alkyloxy group, cycloalkyloxy group, carbonate group,alkylcarbonate group, alkyl carboxylate group, tosylate group, ormesylate group; NR is an alkylamide group or an alkylamino group; and xranges from 2 to about 1000. In some embodiments, the molecular weightof the oligomer or second polymer is weight average molecular weight. Insome embodiments, R is (CH₂)_(y)CH₃, where 0≤y≤14. In some embodiments,OR is (—O(CH₂CH₂O)_(a)—CH₂CH₃), where 1≤a≤6. In some embodiments, R, OR,and NR include a chain structure, a ring structure, or a 3-D structure.In some embodiments, the 3-D structure is selected from the groupconsisting of norbornyl, adamantyl, basketanyl, twistanyl, cubanyl, anddodecahedranyl groups.

In some embodiments, the second crosslinker is one or more selected fromthe group consisting of A-(OH)_(x), A-(OR′)_(x), A-(C═C)_(x), andA-(CC)_(x), where A is a monomer, oligomer, or a second polymer having amolecular weight ranging from 100 to 20,000; R′ is an alkyloxy group, analkenyl group, or an alkynyl group; and x ranges from 2 to about 1000.In some embodiments, R is (CH₂)_(y)CH₃, where 0≤y≤14. In someembodiments, R and OR include a chain structure, a ring structure, or a3-D structure. In some embodiments, the 3-D structure is selected fromthe group consisting of norbornyl, adamantyl, basketanyl, twistanyl,cubanyl, and dodecahedranyl groups.

In some embodiments, the carbon backbone polymer contains crosslinkingsites on the polymer.

In some embodiments, a concentration of the first and secondcrosslinkers ranges from about 20 wt. % to about 50 wt. % of the totalweight of the first and second crosslinkers and the carbon backbonepolymer. In some embodiments, less than about 20 wt. % of thecrosslinkers results in insufficient crosslinking. In some embodiments,more than about 50 wt. % of the crosslinkers provides no or onlynegligible improvement in the crosslinking. In some embodiments, theconcentration of the first crosslinker ranges from about 5 wt. % toabout 40 wt. % of the total weight of the first and second crosslinkersand the carbon backbone polymer. In some embodiments, the concentrationof the second crosslinker ranges from about 5 wt. % to about 40 wt. % ofthe total weight of the first and second crosslinkers and the carbonbackbone polymer. In some embodiments, the concentration of the firstcrosslinker is about the same as the concentration of the secondcrosslinker.

The bottom layer 110 is subjected to a first heating at a temperatureranging from about 100° C. to about 170° C. in some embodiments to forma partially crosslinked layer. In some embodiments, the first heating isat a temperature ranging from about 100° C. to about 150° C.

The viscosity of the bottom layer composition is selected so that itprovides a target thickness when it is spin-coated on the substrate. Insome embodiments, the bottom layer composition has a viscosity ofbetween about 0.1 to about 1×10⁶ Pa s at about 20° C. and is spin coatedon the substrate at about 1500 rpm. The first heating at about 100° C.to about 170° C. causes partial polymer crosslinking and increasesviscosity from about 0.11×10⁶ Pa s to about 100 Pas to about 1×10⁸ Pasin some embodiments. The second heating at about 170° C. to about 300°C. causes further polymer crosslinking and increases the viscosity fromabout 100 Pas to about 1×10⁸ Pa s to a solid state layer. First heatingtemperatures below about 100° C. may result in insufficient partialcrosslinking. First heating temperatures above about 170° C. may resultin negligible additional partial crosslinking, or may prematurelytrigger the second crosslinker. In some embodiments, the bottom layer110 is heated at the first temperature for about 10 seconds to about 5minutes to partially crosslink the bottom layer 110. In someembodiments, the first heating is performed for about 30 seconds toabout 3 minutes. In some embodiments, the second heating is performedfor about 30 seconds to about 3 minutes.

After the first heating, the bottom layer 110 is allowed to cool atabout 20° C. to about 25° C. for about 10 s to about 1 min in someembodiments. Then the bottom layer 110 is subsequently subjected to asecond heating at a second temperature higher than the first temperatureto form a further or fully crosslinked bottom layer 110. In someembodiments, the second temperature ranges from about 170° C. to about300° C. In some embodiments, the second temperature ranges from about180° C. to about 300° C. In some embodiments, the second temperatureranges from about 200° C. to about 280° C. Second heating attemperatures below about 170° C. may result in insufficientcrosslinking. Second heating temperatures above about 300° C. or 400° C.may result in an unacceptable increase in layer reflow or decompositionor degradation of the organic material forming the layer 110. In someembodiments, the layer 110 is heated at the second temperature for about30 seconds to about 3 minutes. In other embodiments, the second heatingis performed for about 30 seconds to about 2 minutes. After the secondheating, the bottom layer is allowed to cool at about 20° C. to about25° C. for about 10 s to about 1 min before performing subsequentprocesses.

FIG. 12 illustrates an example of the crosslinking operations in thebottom layer 110 according to embodiments of the disclosure. In anembodiment, the bottom layer includes a main polymer, such aspolyhydroxystyrene, a low activation energy (Ea) crosslinker with fouralkoxy crosslinking groups, and a high activation energy (Ea)crosslinker with four hydroxyl groups. The bottom layer is subjected toa low temperature baking operation, such as heating at about 130° C.,which triggers the low Ea crosslinker to partially crosslink the mainpolymer. Then, a high temperature baking operation is performed, such asheating at about 250° C., which triggers the high Ea crosslinker to morefully crosslink the main polymer.

In some embodiments, the bottom layer is made of a polymer compositionincluding polymers having one or more of repeating units 1-12 of FIG. 13. In FIG. 13 , a, b, c, d, e, f, g, h, and i are each independently H,—OH, —ROH, —R(OH)₂, —NH₂, —NHR, —NR₂, —SH, —RSH, or —R(SH)₂, wherein atleast one of a, b, c, d, e, f, g, h, and i on each repeating unit 1-12is not H. R, R₁, and R₂ are each independently a C1-C10 alkyl group, aC3-C10 cycloalkyl group, a C1-C10 hydroxyalkyl group, a C2-C10 alkoxygroup, a C2-C10 alkoxy alkyl group, a C2-C10 acetyl group, a C3-C10acetylalkyl group, a C1-C10 carboxyl group, a C2-C10 alkyl carboxylgroup, or a C4-C10 cycloalkyl carboxyl group, and n is 2-1000. Polymersformed of the repeating units 1-12 of FIG. 13 may crosslink upon heatingor exposure to actinic radiation. In some embodiments, the bottom layercomposition includes one or more of a crosslinker or a coupling reagent.The crosslinker crosslinks the bottom layer composition when heated orexposed to actinic radiation. Examples of repeating units 1-12 accordingto embodiments of the disclosure are shown in FIGS. 14A, 14B, and 14C.In some embodiments, each of the repeating units include two or morefunctional groups.

In some embodiments, the polymer includes repeating units having one ormore of hydroxyl groups, amine groups, or mercapto groups. In someembodiments, each repeating unit includes at least two functional groupsselected from one or more of —OH, —ROH, —R(OH)₂, —NH₂, —NHR, —NR₂, —SH,—RSH, or —R(SH)₂, wherein R is a C1-C10 alkyl group, a C3-C10 cycloalkylgroup, a C1-C10 hydroxyalkyl group, a C2-C10 alkoxy group, a C2-C10alkoxy alkyl group, a C2-C10 acetyl group, a C3-C10 acetylalkyl group, aC1-C10 carboxyl group, a C2-C10 alkyl carboxyl group, or a C4-C10cycloalkyl carboxyl group.

In some embodiments, the bottom layer composition includes a polymerhaving one or more of the repeating units disclosed in FIGS. 13-14Cdisclosed herein. In some embodiments, at least one repeating unitincludes three or more of —OH, —ROH, —R(OH)₂, —NH₂, —NHR, —NR₂, —SH,—RSH, or —R(SH)₂. In some embodiments, the polymer includes at least onerepeating unit having three or more —OH groups.

In some embodiments the crosslinker has the following structure:

In other embodiments, the crosslinker has the following structure:

wherein C is carbon, n ranges from 1 to 15; A and B independentlyinclude a hydrogen atom, a hydroxyl group, a halide, an aromatic carbonring, or a straight or cyclic alkyl, alkoxyl/fluoro, alkyl/fluoroalkoxylchain having a carbon number of between 1 and 12, and each carbon Ccontains A and B; a first terminal carbon C at a first end of a carbon Cchain includes X and a second terminal carbon C at a second end of thecarbon chain includes Y, wherein X and Y independently include an aminegroup, a thiol group, a hydroxyl group, an isopropyl alcohol group, oran isopropyl amine group, except when n=1 then X and Y are bonded to thesame carbon C. Specific examples of materials that may be used as thecrosslinker include the following:

Alternatively, instead of or in addition to the crosslinker being addedto the bottom layer composition, a coupling reagent is added in someembodiments. The coupling reagent assists the crosslinking reaction byreacting with the groups on the hydrocarbon structure in the polymerbefore the crosslinker, allowing for a reduction in the reaction energyof the crosslinking reaction and an increase in the rate of reaction.The bonded coupling reagent then reacts with the crosslinker, therebycoupling the crosslinker to the polymer.

Alternatively, in some embodiments in which the coupling reagent isadded to the bottom layer composition without the crosslinker, thecoupling reagent is used to couple one group from one of the hydrocarbonstructures in the polymer to a second group from a separate one of thehydrocarbon structures in order to crosslink and bond the two polymerstogether. However, in such an embodiment the coupling reagent, unlikethe crosslinker, does not remain as part of the polymer, and onlyassists in bonding one hydrocarbon structure directly to anotherhydrocarbon structure.

In some embodiments, the coupling reagent has the following structure:

where R is a carbon atom, a nitrogen atom, a sulfur atom, or an oxygenatom; M includes a chlorine atom, a bromine atom, an iodine atom, —NO₂;—SO₃—; —H—; —CN; —NCO, —OCN; —CO₂—; —OH; —OR*, —OC(O)CR*; —SR,—SO₂N(R*)₂; —SO₂R*; SOR; —OC(O)R*; —C(O)OR*; —C(O)R*; —Si(OR*)₃;—Si(R*)₃; epoxy groups, or the like; and R* is a substituted orunsubstituted C1-C12 alkyl, C1-C12 aryl, C1-C12 aralkyl, or the like.Specific examples of materials used as the coupling reagent in someembodiments include the following:

In some embodiments, the bottom layer 110 is formed by preparing abottom layer coating composition of a polymer and optional crosslinkeror coupling reagent in a solvent. The solvent can be any suitablesolvent for dissolving the polymer. The bottom layer coating compositionis applied over a substrate 10 or device features, such as by spincoating. Then the bottom layer composition is baked to dry the bottomlayer and crosslink the polymer, as explained herein.

In some embodiments, the bottom layer composition includes a solvent. Insome embodiments, the solvent is chosen such that the polymers andadditives, such as crosslinkers, can be evenly dissolved into thesolvent and dispensed upon the substrate.

In some embodiments, the solvent is an organic solvent, and includes oneor more of any suitable solvent such as ketones, alcohols, polyalcohols,ethers, glycol ethers, cyclic ethers, aromatic hydrocarbons, esters,propionates, lactates, lactic esters, alkylene glycol monoalkyl ethers,alkyl lactates, alkyl alkoxypropionates, cyclic lactones, monoketonecompounds that contain a ring, alkylene carbonates, alkyl alkoxyacetate,alkyl pyruvates, lactate esters, ethylene glycol alkyl ether acetates,diethylene glycols, propylene glycol alkyl ether acetates, alkyleneglycol alkyl ether esters, alkylene glycol monoalkyl esters, or thelike.

Specific examples of materials that may be used as the solvent for thebottom layer include, acetone, methanol, ethanol, propanol, isopropanol(IPA), n-butanol, toluene, xylene, 4-hydroxy-4-methyl-2-pentanone,tetrahydrofuran (THF), methyl ethyl ketone, cyclohexanone (CHN), methylisoamyl ketone, 2-heptanone (MAK), ethylene glycol, 1-ethoxy-2-propanol,methyl isobutyl carbinol (MIBC), ethylene glycol monoacetate, ethyleneglycol dimethyl ether, ethylene glycol methylethyl ether, ethyleneglycol monoethyl ether, methyl cellosolve acetate, ethyl cellosolveacetate, diethylene glycol, diethylene glycol monoacetate, diethyleneglycol monomethyl ether, diethylene glycol diethyl ether, diethyleneglycol dimethyl ether, diethylene glycol ethylmethyl ether,diethethylene glycol monoethyl ether, diethylene glycol monobutyl ether,ethyl 2-hydroxypropionate, methyl 2-hydroxy-2-methylpropionate, ethyl2-hydroxy-2-methylpropionate, ethyl ethoxyacetate, ethyl hydroxyacetate,methyl 2-hydroxy-2-methylbutanate, methyl 3-methoxypropionate, ethyl3-methoxypropionate, methyl 3-ethoxypropionate, ethyl3-ethoxypropionate, methyl acetate, ethyl acetate, propyl acetate,n-butyl acetate (nBA), methyl lactate, ethyl lactate (EL), propyllactate, butyl lactate, propylene glycol, propylene glycol monoacetate,propylene glycol monoethyl ether acetate, propylene glycol monomethylether acetate, propylene glycol monopropyl methyl ether acetate,propylene glycol monobutyl ether acetate, propylene glycol monobutylether acetate, propylene glycol monomethyl ether propionate, propyleneglycol monoethyl ether propionate, propylene glycol methyl etheracetate, propylene glycol ethyl ether acetate, ethylene glycolmonomethyl ether acetate, ethylene glycol monoethyl ether acetate,propylene glycol monomethyl ether, propylene glycol monoethyl ether,propylene glycol monopropyl ether, propylene glycol monobutyl ether,ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethyl3-ethoxypropionate, methyl 3-methoxypropionate, methyl3-ethoxypropionate, and ethyl 3-methoxypropionate, β-propiolactone,β-butyrolactone, γ-butyrolactone (GBL), α-methyl-γ-butyrolactone,β-methyl-γ-butyrolactone, γ-valerolactone, γ-caprolactone, γ-octanoiclactone, α-hydroxy-γ-butyrolactone, 2-butanone, 3-methylbutanone,pinacolone, 2-pentanone, 3-pentanone, 4-methyl-2-pentanone,2-methyl-3-pentanone, 4,4-dimethyl-2-pentanone,2,4-dimethyl-3-pentanone, 2,2,4,4-tetramethyl-3-pentanone, 2-hexanone,3-hexanone, 5-methyl-3-hexanone, 3-heptanone, 4-heptanone,2-methyl-3-heptanone, 5-methyl-3-heptanone, 2,6-dimethyl-4-heptanone,2-octanone, 3-octanone, 2-nonanone, 3-nonanone, 5-nonanone, 2-decanone,3-decanone, 4-decanone, 5-hexene-2-one, 3-pentene-2-one, cyclopentanone,2-methylcyclopentanone, 3-methylcyclopentanone,2,2-dimethylcyclopentanone, 2,4,4-trimethylcyclopentanone,3-methylcyclohexanone, 4-methylcyclohexanone, 4-ethylcyclohexanone,2,2-dimethylcyclohexanone, 2,6-dimethylcyclohexanone,2,2,6-trimethylcyclohexanone, cycloheptanone, 2-methylcycloheptanone,3-methylcycloheptanone, propylene carbonate, vinylene carbonate,ethylene carbonate, butylene carbonate, acetate-2-methoxyethyl,acetate-2-ethoxyethyl, acetate-2-(2-ethoxyethoxy)ethyl,acetate-3-methoxy-3-methylbutyl, acetate-1-methoxy-2-propyl, dipropyleneglycol, monomethylether, monoethylether, monopropylether,monobutylether, monophenylether, dipropylene glycol monoacetate,dioxane, methyl pyruvate, ethyl pyruvate, propyl pyruvate, methylmethoxypropionate, ethyl ethoxypropionate, n-methylpyrrolidone (NMP),2-methoxyethyl ether (diglyme), ethylene glycol monomethyl ether,propylene glycol monomethyl ether, methyl propionate, ethyl propionate,ethyl ethoxy propionate, methylethyl ketone, cyclopentanone, ethyl3-ethoxypropionate, propylene glycol methyl ether acetate (PGMEA),methylene cellosolve, 2-ethoxyethanol, N-methylformamide,N,N-dimethylformamide (DMF), N-methylformanilide, N-methylacetamide,N,N-dimethylacetamide, dimethylsulfoxide, benzyl ethyl ether, dihexylether, acetonylacetone, isophorone, caproic acid, caprylic acid,1-octanol, 1-nonanol, benzyl alcohol, benzyl acetate, ethyl benzoate,diethyl oxalate, diethyl maleate, phenyl cellosolve acetate, or thelike.

In some embodiments, the middle layer 115 includes a silicon-containinglayer (e.g., a silicon hard mask material). The middle layer 115 mayinclude a silicon-containing organic or inorganic polymer. In otherembodiments, the middle layer includes a siloxane polymer. In otherembodiments, the middle layer 115 includes silicon oxide (e.g., spin-onglass (SOG)), silicon nitride, silicon oxynitride, polycrystallinesilicon; and/or other suitable materials. The middle layer 115 may bebonded to adjacent layers (e.g., bottom layer 110 and upper layer 120),such as by covalent bonding, hydrogen bonding, orhydrophilic-to-hydrophilic forces.

Thus, the middle layer 115 may include a composition that allows acovalent bond to be formed between the middle layer and the overlyingphotoresist layer 115 after an exposure process and/or subsequent bakingprocess.

In some embodiments, the middle layer 115 includes a component having aphotoacid generator (PAG). The PAG generates an acid that interacts withthe exposed photoresist layer 120. In some embodiments, the middle layer115 includes a polysiloxane having pendant PAG groups.

In some embodiments, a middle layer composition includes siloxanemonomers and siloxane monomers with photoacid generator substituents. Insome embodiments, a photoacid generator compound is first reacted with asiloxane, and then the reaction product, a siloxane having a photoacidgenerator group, is applied over the bottom layer 110, and thenpolymerized or crosslinked over the bottom layer 110. In someembodiments, the middle layer composition is a mixture of aspin-on-glass (SOG) and a photoacid generator. In some embodiments, thephotoacid generator is first reacted with an SOG precursor and thenreaction product is applied to the bottom layer 110 and cured. In someembodiments, a silicon-containing material and a photoacid generator aremixed together and the mixture is applied over the bottom layer. Themixture is subsequently heated to form a reaction product of thephotoacid generator and the silicon-containing material after applyingthe mixture over the first layer in some embodiments. The reactionproduct is further heated to cause the reaction product to polymerize orcrosslink. In some embodiments, the substrate or the middle layercomposition is heated during the spin-coating operation, and the middlelayer composition polymerizes or crosslinks during the applicationoperation. The components of the middle layer composition are mixed in asolvent in some embodiments.

In some embodiments, the solvent is any of the solvents discussed hereinused for forming the bottom layer. In some embodiments, the middle layercomposition is applied over the bottom layer 110, and then the middlelayer 115 is heated at temperature ranging from about 150° C. to about300° C., as discussed herein in reference to operation S115 (FIG. 1 ).In some embodiments, the middle layer 115 is heated at temperatureranging from about 200° C. to about 250° C. The baking operation S120causes the components of the middle layer composition to react,polymerize, or crosslink.

The polymerization reaction of siloxane monomers initiated by the bakingoperation S120 according to some embodiments is illustrated in FIG. 15A.In some embodiments, some of the siloxane monomers include pendantphotoacid generator groups. As illustrated in FIG. 15B, in someembodiments, a mixture of siloxane monomers 155 and siloxane monomerssubstituted with PAG groups 160 is baked under baking conditions asdisclosed herein. As a result of the baking, the monomers polymerize andcrosslink in some embodiments, as shown in FIG. 15B.

A siloxane monomer having a PAG group according to some embodiments isshown below:

where A is a direct bond, a C1-C5 alkyl group, a C1-C5 cycloalkyl group,a C1-C5 hydroxy alkyl group, a C1-C5 alkoxy group, a C1-C5 alkoxyl alkylgroup, a C1-05 acetyl group, a C1-05 acetyl alkyl group, a C1-C5carboxyl group, or a C1-C5 alkyl carboxyl group; R₁ and R₂ are eachindependently a C6-C12 aryl group, a C6-C12 alkyl group, a C6-C12cycloalkyl group, a C6-C12 hydroxy alkyl group, a C6-C12 alkoxy group, aC6-C12 alkoxyl alkyl group, a C6-C12 acetyl group, a C6-C12 acetyl alkylgroup, a C6-C12 carboxyl group, a C6-C12 alkyl carboxyl group, a C6-C12cycloalkyl carboxyl group, a C3-C15 saturated or unsaturated hydrocarbonring or a C2-C15 heterocyclic group; R₃ is a C1-C20 fluorocarbon group,a C6-C20 aryl group, or a C10-C20 adamantyl group; and a, b, d, and dare each independently H or a C1-C6 alkyl group. In some embodiments,R1, R2, and R3 independently contain one to three iodine atoms.

The photoacid generator group can be any suitable photoacid generator.In some embodiments, the photoacid generator group includes an anion anda cation. In some embodiments, the photoacid generator group includes acationic group bound to the siloxane. In some embodiments, the photoacidgenerator includes an onium cation. In some embodiments, the oniumcation is a sulfonium. In some embodiments, the sulfonium is a triphenylsulfonium. In some embodiments, the anion is a sulfite anion. In someembodiments, the anion is a sulfite anion with an organic groupsubstitutent. In some embodiments, the embodiments the anion includes afluorocarbon substituent group.

FIGS. 16A and 16B illustrate examples of photoacid generator monomerunits according to embodiments of the disclosure.

FIG. 17 illustrates the acid generation reaction according toembodiments of the disclosure. A photoacid generator including a cationand an anion is bonded to a polymer. The cationic polymer bound PAG doesnot diffuse to the photosensitive layer 120 because it is bound to themiddle layer polymer during the photoresist coating process. Whenexposed to actinic radiation, the anion (the acid) is released from thePAG group. After exposure to actinic radiation, the generated acid isfree to diffuse to the photosensitive layer. The subsequent postexposure baking operation S140, accelerates the diffusion of the acidinto the exposed portions of the photosensitive layer 120.

The photosensitive layer 120 is a photoresist layer that is patterned byexposure to actinic radiation in some embodiments. Typically, thechemical properties of the photoresist regions struck by incidentradiation change in a manner that depends on the type of photoresistused. Photoresist layers 120 are either positive tone resists ornegative tone resists. A positive tone resist refers to a photoresistmaterial that when exposed to radiation, such as UV light, becomessoluble in a developer, while the region of the photoresist that isnon-exposed (or exposed less) is insoluble in the developer. A negativetone resist, on the other hand, refers to a photoresist material thatwhen exposed to radiation becomes insoluble in the developer, while theregion of the photoresist that is non-exposed (or exposed less) issoluble in the developer. The region of a negative resist that becomesinsoluble upon exposure to radiation may become insoluble due to across-linking reaction caused by the exposure to radiation.

Whether a resist is a positive tone or negative tone may depend on thetype of developer used to develop the resist. For example, some positivetone photoresists provide a positive pattern, (i.e.—the exposed regionsare removed by the developer), when the developer is an aqueous-baseddeveloper, such as a tetramethylammonium hydroxide (TMAH) solution. Onthe other hand, the same photoresist provides a negative pattern(i.e.—the unexposed regions are removed by the developer) when thedeveloper is an organic solvent. Further, in some negative tonephotoresists developed with the TMAH solution, the unexposed regions ofthe photoresist are removed by the TMAH, and the exposed regions of thephotoresist, that undergo cross-linking upon exposure to actinicradiation, remain on the substrate after development.

In some embodiments, resist compositions according to embodiments of thedisclosure, such as a photoresist, include a polymer or a polymerizablemonomer or oligomer along with one or more photoactive compounds (PACs).In some embodiments, the concentration of the polymer, monomer, oroligomer ranges from about 1 wt. % to about 75 wt. % based on the totalweight of the resist composition. In other embodiments, theconcentration of the polymer, monomer, or oligomer ranges from about 5wt. % to about 50 wt. %. At concentrations of the polymer, monomer, oroligomer below the disclosed ranges the polymer, monomer, or oligomerhas negligible effect on the resist performance. At concentrations abovethe disclosed ranges, there is no substantial improvement in resistperformance or there is degradation in the formation of consistentresist layers.

In some embodiments, the polymerizable monomer or oligomer includes anacrylic acid, an acrylate, a hydroxystyrene, or an alkylene. In someembodiments, the polymer includes a hydrocarbon structure (such as analicyclic hydrocarbon structure) that contains one or more groups thatwill decompose (e.g., acid labile groups) or otherwise react when mixedwith acids, bases, or free radicals generated by the PACs (as furtherdescribed below). In some embodiments, the hydrocarbon structureincludes a repeating unit that forms a skeletal backbone of the polymerresin. This repeating unit may include acrylic esters, methacrylicesters, crotonic esters, vinyl esters, maleic diesters, fumaricdiesters, itaconic diesters, (meth)acrylonitrile, (meth)acrylamides,styrenes, vinyl ethers, combinations of these, or the like.

Specific structures that are utilized for the repeating unit of thehydrocarbon structure in some embodiments, include one or more of methylacrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butylacrylate, isobutyl acrylate, tert-butyl acrylate, n-hexyl acrylate,2-ethylhexyl acrylate, acetoxyethyl acrylate, phenyl acrylate,2-hydroxyethyl acrylate, 2-methoxyethyl acrylate, 2-ethoxyethylacrylate, 2-(2-methoxyethoxy)ethyl acrylate, cyclohexyl acrylate, benzylacrylate, 2-alkyl-2-adamantyl (meth)acrylate ordialkyl(1-adamantyl)methyl (meth)acrylate, methyl methacrylate, ethylmethacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butylmethacrylate, isobutyl methacrylate, tert-butyl methacrylate, n-hexylmethacrylate, 2-ethylhexyl methacrylate, acetoxyethyl methacrylate,phenyl methacrylate, 2-hydroxyethyl methacrylate, 2-methoxyethylmethacrylate, 2-ethoxyethyl methacrylate, 2-(2-methoxyethoxy)ethylmethacrylate, cyclohexyl methacrylate, benzyl methacrylate,3-chloro-2-hydroxypropyl methacrylate, 3-acetoxy-2-hydroxypropylmethacrylate, 3-chloroacetoxy-2-hydroxypropyl methacrylate, butylcrotonate, hexyl crotonate, or the like. Examples of the vinyl estersinclude vinyl acetate, vinyl propionate, vinyl butylate, vinylmethoxyacetate, vinyl benzoate, dimethyl maleate, diethyl maleate,dibutyl maleate, dimethyl fumarate, diethyl fumarate, dibutyl fumarate,dimethyl itaconate, diethyl itaconate, dibutyl itaconate, acrylamide,methyl acrylamide, ethyl acrylamide, propyl acrylamide, n-butylacrylamide, tert-butyl acrylamide, cyclohexyl acrylamide, 2-methoxyethylacrylamide, dimethyl acrylamide, diethyl acrylamide, phenyl acrylamide,benzyl acrylamide, methacrylamide, methyl methacrylamide, ethylmethacrylamide, propyl methacrylamide, n-butyl methacrylamide,tert-butyl methacrylamide, cyclohexyl methacrylamide, 2-methoxyethylmethacrylamide, dimethyl methacrylamide, diethyl methacrylamide, phenylmethacrylamide, benzyl methacrylamide, methyl vinyl ether, butyl vinylether, hexyl vinyl ether, methoxyethyl vinyl ether, dimethylaminoethylvinyl ether, or the like. Examples of styrenes include styrene, methylstyrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropylstyrene, butyl styrene, methoxy styrene, butoxy styrene, acetoxystyrene, hydroxy styrene, chloro styrene, dichloro styrene, bromostyrene, vinyl methyl benzoate, α-methyl styrene, maleimide,vinylpyridine, vinylpyrrolidone, vinylcarbazole, combinations of these,or the like.

In some embodiments, the polymer is a polyhydroxystyrene, a polymethylmethacrylate, or a polyhydroxystyrene-t-butyl acrylate, e.g.—

In some embodiments, the repeating unit of the hydrocarbon structurealso has either a monocyclic or a polycyclic hydrocarbon structuresubstituted into it, or the monocyclic or polycyclic hydrocarbonstructure is the repeating unit, in order to form an alicyclichydrocarbon structure. Specific examples of monocyclic structures insome embodiments include bicycloalkane, tricycloalkane,tetracycloalkane, cyclopentane, cyclohexane, or the like. Specificexamples of polycyclic structures in some embodiments includeadamantane, norbornane, isobornane, tricyclodecane, tetracyclododecane,or the like.

The group which will decompose, otherwise known as a leaving group or,in some embodiments in which the PAC is a photoacid generator, an acidlabile group, is attached to the hydrocarbon structure so that, it willreact with the acids/bases/free radicals generated by the PACs duringexposure. In some embodiments, the group which will decompose is acarboxylic acid group, a fluorinated alcohol group, a phenolic alcoholgroup, a sulfonic group, a sulfonamide group, a sulfonylimido group, an(alkylsulfonyl) (alkylcarbonyl)methylene group, an(alkylsulfonyl)(alkyl-carbonyl)imido group, abis(alkylcarbonyl)methylene group, a bis(alkylcarbonyl)imido group, abis(alkylsulfonyl)methylene group, a bis(alkylsulfonyl)imido group, atris(alkylcarbonyl methylene group, a tris(alkylsulfonyl)methylenegroup, combinations of these, or the like. Specific groups that are usedfor the fluorinated alcohol group include fluorinated hydroxyalkylgroups, such as a hexafluoroisopropanol group in some embodiments.Specific groups that are used for the carboxylic acid group includeacrylic acid groups, methacrylic acid groups, or the like.

In some embodiments, the polymer also includes other groups attached tothe hydrocarbon structure that help to improve a variety of propertiesof the polymerizable resin. For example, inclusion of a lactone group tothe hydrocarbon structure assists to reduce the amount of line edgeroughness after the photoresist has been developed, thereby helping toreduce the number of defects that occur during development. In someembodiments, the lactone groups include rings having five to sevenmembers, although any suitable lactone structure may alternatively beused for the lactone group.

In some embodiments, the polymer includes groups that can assist inincreasing the adhesiveness of the photoresist layer 120 to theunderlying middle layer 115. Polar groups may be used to help increasethe adhesiveness. Suitable polar groups include hydroxyl groups, cyanogroups, or the like, although any suitable polar group may,alternatively, be used.

Optionally, the polymer includes one or more alicyclic hydrocarbonstructures that do not also contain a group, which will decompose insome embodiments. In some embodiments, the hydrocarbon structure thatdoes not contain a group which will decompose includes structures suchas 1-adamantyl(meth)acrylate, tricyclodecanyl (meth)acrylate, cyclohexyl(methacrylate), combinations of these, or the like.

In some embodiments, such as when EUV radiation is used, the photoresistcompositions according to the present disclosure are metal-containingresists. The metal-containing resists include metallic cores complexedwith one or more ligands in a solvent. In some embodiments, the resistincludes metal particles. In some embodiments, the metal particles arenanoparticles. As used herein, nanoparticles are particles having anaverage particle size between about 1 nm and about 20 nm. In someembodiments, the metallic cores, including from 1 to about 18 metalparticles, are complexed with one or more organic ligands in a solvent.In some embodiments, the metallic cores include 3, 6, 9, or more metalnanoparticles complexed with one or more organic ligands in a solvent.

In some embodiments, the metal particle is one or more of titanium (Ti),zinc (Zn), zirconium (Zr), nickel (Ni), cobalt (Co), manganese (Mn),copper (Cu), iron (Fe), strontium (Sr), tungsten (W), vanadium (V),chromium (Cr), tin (Sn), hafnium (Hf), indium (In), cadmium (Cd),molybdenum (Mo), tantalum (Ta), niobium (Nb), aluminum (Al), cesium(Cs), barium (Ba), lanthanum (La), cerium (Ce), silver (Ag), antimony(Sb), combinations thereof, or oxides thereof. In some embodiments, themetal particles include one or more selected from the group consistingof Ce, Ba, La, In, Sn, Ag, Sb, and oxides thereof.

In some embodiments, the metal nanoparticles have an average particlesize between about 2 nm and about 5 nm. In some embodiments, the amountof metal nanoparticles in the resist composition ranges from about 0.5wt. % to about 15 wt. % based on the weight of the nanoparticles and thesolvent. In some embodiments, the amount of nanoparticles in the resistcomposition ranges from about 5 wt. % to about 10 wt. % based on theweight of the nanoparticles and the solvent. In some embodiments, theconcentration of the metal particles ranges from 1 wt. % to 7 wt. %based on the weight of the solvent and the metal particles. Below about0.5 wt. % metal nanoparticles, the resist coating is too thin. Aboveabout 15 wt. % metal nanoparticles, the resist coating is too thick andviscous.

In some embodiments, the metallic core is complexed by a ligand, whereinthe ligand includes branched or unbranched, cyclic or non-cyclic,saturated organic groups, including C1-C7 alkyl groups or C1-C7fluoroalkyl groups. The C1-C7 alkyl groups or C1-C7 fluoroalkyl groupsinclude one or more substituents selected from the group consisting of—CF₃, —SH, —OH, ═O, —S—, —P—, —PO₂, —C(═O)SH, —C(═O)OH, —C(═O)O—, —O—,—N—, —C(═O)NH, —SO₂OH, —SO₂SH, —SOH, and —SO₂—. In some embodiments, theligand includes one or more substituents selected from the groupconsisting of —CF₃, —OH, —SH, and —C(═O)OH substituents.

In some embodiments, the ligand is a carboxylic acid or sulfonic acidligand. For example, in some embodiments, the ligand is a methacrylicacid. In some embodiments, the metal particles are nanoparticles, andthe metal nanoparticles are complexed with ligands including aliphaticor aromatic groups. The aliphatic or aromatic groups may be unbranchedor branched with cyclic or noncyclic saturated pendant groups containing1-9 carbons, including alkyl groups, alkenyl groups, and phenyl groups.The branched groups may be further substituted with oxygen or halogen.In some embodiments, each metal particle is complexed by 1 to 25 ligandunits. In some embodiments, each metal particle is complexed by 3 to 18ligand units. In some embodiments, the organometallic

In some embodiments, the resist composition includes about 0.1 wt. % toabout 20 wt. % of the ligands based on the total weight of the resistcomposition. In some embodiments, the resist includes about 1 wt. % toabout 10 wt. % of the ligands. In some embodiments, the ligandconcentration is about 10 wt. % to about 40 wt. % based on the weight ofthe metal particles and the weight of the ligands. Below about 10 wt. %,ligand, the organometallic photoresist does not function well. Aboveabout 40 wt. %, ligand, it is difficult to form a consistent photoresistlayer. In some embodiments, the ligand(s) is dissolved at about a 5 wt.% to about 10 wt. % weight range in a coating solvent, such as propyleneglycol methyl ether acetate (PGMEA) based on the weight of the ligand(s)and the solvent.

In some embodiments, the copolymers and the PACs, along with any desiredadditives or other agents, are added to the solvent for application.Once added, the mixture is then mixed in order to achieve a homogenouscomposition throughout the photoresist to ensure that there are nodefects caused by uneven mixing or nonhomogeneous composition of thephotoresist. Once mixed together, the photoresist may either be storedprior to its usage or used immediately.

The solvent can be any suitable solvent, including the solvents used tocoat the bottom layer composition, as described herein.

Some embodiments of the photoresist include one or more photoactivecompounds (PACs). The PACs are photoactive components, such as photoacidgenerators (PAG), photobase (PBG) generators, photo decomposable bases(PDB), free-radical generators, or the like. The PACs may bepositive-acting or negative-acting. In some embodiments in which thePACs are a photoacid generator, the PACs include halogenated triazines,onium salts, diazonium salts, aromatic diazonium salts, phosphoniumsalts, sulfonium salts, iodonium salts, imide sulfonate, oximesulfonate, diazodisulfone, disulfone, o-nitrobenzylsulfonate, sulfonatedesters, halogenated sulfonyloxy dicarboximides, diazodisulfones,α-cyanooxyamine-sulfonates, imidesulfonates, ketodiazosulfones,sulfonyldiazoesters, 1,2-di(arylsulfonyl)hydrazines, nitrobenzyl esters,and the s-triazine derivatives, combinations of these, or the like.

Specific examples of photoacid generators includeα-(trifluoromethylsulfonyloxy)-bicyclo[2.2.1]hept-5-ene-2,3-dicarb-o-ximide(MDT), N-hydroxy-naphthalimide (DDSN), benzoin tosylate,t-butylphenyl-α-(p-toluenesulfonyloxy)-acetate andt-butyl-α-(p-toluenesulfonyloxy)-acetate, triarylsulfonium anddiaryliodonium hexafluoroantimonates, hexafluoroarsenates,trifluoromethanesulfonates, iodonium perfluorooctanesulfonate,N-camphorsulfonyloxynaphthalimide,N-pentafluorophenylsulfonyloxynaphthalimide, ionic iodonium sulfonatessuch as diaryl iodonium (alkyl or aryl)sulfonate andbis-(di-t-butylphenyl)iodonium camphanylsulfonate,perfluoroalkanesulfonates such as perfluoropentanesulfonate,perfluorooctanesulfonate, perfluoromethanesulfonate, aryl (e.g., phenylor benzyl)triflates such as triphenylsulfonium triflate orbis-(t-butylphenyl)iodonium triflate; pyrogallol derivatives (e.g.,trimesylate of pyrogallol), trifluoromethanesulfonate esters ofhydroxyimides, α,α′-bis-sulfonyl-diazomethanes, sulfonate esters ofnitro-substituted benzyl alcohols, naphthoquinone-4-diazides, alkyldisulfones, or the like.

In some embodiments, the PAG in the photosensitive layer 120 includes ananion or a cation that is different from an anion or a cation of thephotoacid generator bound to the polymer in the middle layer 115.

In some embodiments in which the PACs are free-radical generators, thePACs include n-phenylglycine; aromatic ketones, including benzophenone,N,N′-tetramethyl-4,4′-diaminobenzophenone,N,N′-tetraethyl-4,4′-diaminobenzophenone,4-methoxy-4′-dimethylaminobenzo-phenone,3,3′-dimethyl-4-methoxybenzophenone,p,p′-bis(dimethylamino)benzo-phenone,p,p′-bis(diethylamino)-benzophenone; anthraquinone,2-ethylanthraquinone; naphthaquinone; and phenanthraquinone; benzoinsincluding benzoin, benzoinmethylether, benzoinisopropylether,benzoin-n-butylether, benzoin-phenylether, methylbenzoin andethylbenzoin; benzyl derivatives, including dibenzyl,benzyldiphenyldisulfide, and benzyldimethylketal; acridine derivatives,including 9-phenylacridine, and 1,7-bis(9-acridinyl)heptane;thioxanthones, including 2-chlorothioxanthone, 2-methylthioxanthone,2,4-diethylthioxanthone, 2,4-dimethylthioxanthone, and2-isopropylthioxanthone; acetophenones, including1,1-dichloroacetophenone, p-t-butyldichloro-acetophenone,2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, and2,2-dichloro-4-phenoxyacetophenone; 2,4,5-triarylimidazole dimers,including 2-(o-chlorophenyl)-4,5-diphenylimidazole dimer,2-(o-chlorophenyl)-4,5-di-(m-methoxyphenyl imidazole dimer,2-(o-fluorophenyl)-4,5-diphenylimidazole dimer,2-(o-methoxyphenyl)-4,5-diphenylimidazole dimer,2-(p-methoxyphenyl)-4,5-diphenylimidazole dimer,2,4-di(p-methoxyphenyl)-5-phenylimidazole dimer,2-(2,4-dimethoxyphenyl)-4,5-diphenylimidazole dimer and2-(p-methylmercaptophenyl)-4,5-diphenylimidazole dimmer; combinations ofthese, or the like.

As one of ordinary skill in the art will recognize, the chemicalcompounds listed herein are merely intended as illustrated examples ofthe PACs and are not intended to limit the embodiments to only thosePACs specifically described. Rather, any suitable PAC may be used, andall such PACs are fully intended to be included within the scope of thepresent embodiments.

In some embodiments, a crosslinker or coupling reagent is added to thephotoresist. The crosslinker reacts with one group from one of thehydrocarbon structures in the polymer resin and also reacts with asecond group from a separate one of the hydrocarbon structures in orderto crosslink and bond the two hydrocarbon structures together. Thisbonding and crosslinking increases the molecular weight of the polymerproducts of the crosslinking reaction and increases the overall linkingdensity of the photoresist. Such an increase in density and linkingdensity helps to improve the resist pattern. The coupling reagentassists the crosslinking reaction. The crosslinker or coupling reagentcan be any of the crosslinkers or coupling reagents disclosed herein inreference to the bottom layer.

The individual components of the photoresist are placed into a solventin order to aid in the mixing and dispensing of the photoresist. To aidin the mixing and dispensing of the photoresist, the solvent is chosenat least in part based upon the materials chosen for the polymer resinas well as the PACs. In some embodiments, the solvent is chosen suchthat the polymer resin and the PACs can be evenly dissolved into thesolvent and dispensed upon the layer to be patterned.

In some embodiments, a quencher is added to the photoresist in someembodiments to inhibit diffusion of the generated acids/bases/freeradicals within the photoresist. The quencher improves the resistpattern configuration as well as the stability of the photoresist overtime.

Another additive added to the photoresist in some embodiments is astabilizer, which assists in preventing undesired diffusion of the acidsgenerated during exposure of the photoresist.

Another additive added to the photoresist in some embodiments is adissolution inhibitor to help control dissolution of the photoresistduring development.

A coloring agent is another additive added to the photoresist in someembodiments of the photoresist. The coloring agent observers examine thephotoresist and find any defects that may need to be remedied prior tofurther processing.

Surface leveling agents are added to the photoresist in some embodimentsto assist a top surface of the photoresist to be level, so thatimpinging light will not be adversely modified by an unlevel surface.

Once ready, the photoresist material is applied over the middle layer115, as shown in FIG. 4 , to form a photoresist layer 120. In someembodiments, the photoresist is applied using a process such as aspin-on coating process, a dip coating method, an air-knife coatingmethod, a curtain coating method, a wire-bar coating method, a gravurecoating method, a lamination method, an extrusion coating method,combinations of these, or the like. In some embodiments, the photoresistlayer 120 thickness ranges from about 10 nm to about 300 nm.

In some embodiments, the developer 57 is applied to the photoresistlayer 120 using a spin-on process during the development operation S145.In the spin-on process, the developer 57 is applied to the photoresistlayer 120 from above the photoresist layer 120 while thephotoresist-coated substrate is rotated, as shown in FIG. 6 . In someembodiments, the developer 57 is supplied at a rate of between about 5ml/min and about 800 ml/min, while the photoresist coated substrate 10is rotated at a speed of between about 100 rpm and about 2000 rpm. Insome embodiments, the developer is at a temperature of between about 10°C. and about 80° C. The development operation continues for betweenabout 30 seconds to about 10 minutes in some embodiments.

While the spin-on operation is one suitable method for developing thephotoresist layer 120 after exposure, it is intended to be illustrativeand is not intended to limit the embodiment. Rather, any suitabledevelopment operations, including dip processes, puddle processes, andspray-on methods, may alternatively be used. All such developmentoperations are included within the scope of the embodiments.

In some embodiments, the photoresist developer 57 includes a solvent,and an acid or a base. In some embodiments, the concentration of thesolvent is from about 60 wt. % to about 99 wt. % based on the totalweight of the photoresist developer. The acid or base concentration isfrom about 0.001 wt. % to about 20 wt. % based on the total weight ofthe photoresist developer. In certain embodiments, the acid or baseconcentration in the developer is from about 0.01 wt. % to about 15 wt.% based on the total weight of the photoresist developer.

In some embodiments, the developer is an aqueous solution, such as anaqueous solution of tetramethylammonium hydroxide. In other embodiments,the developer 57 is an organic solvent. The organic solvent can be anysuitable solvent. In some embodiments, the solvent is one or moreselected from propylene glycol methyl ether acetate (PGMEA), propyleneglycol monomethyl ether (PGME), 1-ethoxy-2-propanol (PGEE),γ-butyrolactone (GBL), cyclohexanone (CHN), ethyl lactate (EL),methanol, ethanol, propanol, n-butanol, 4-methyl-2-pentanol, acetone,methyl ethyl ketone, dimethylformamide (DMF), isopropanol (IPA),tetrahydrofuran (THF), methyl isobutyl carbinol (MIBC), n-butyl acetate(nBA), 2-heptanone (MAK), tetrahydrofuran (THF), and dioxane.

In some embodiments, the trilayer resist of the present disclosure isused in the manufacture of semiconductor devices, such as a gatestructure of a field effect transistor (FET). The embodiments such asthose disclosed herein are generally applicable not only to planar FETsbut also to a fin FET (FinFET), a double-gate FET, a surround-gate FET,an omega-gate FET or a gate-all-around (GAA) FET, and/or nanowiretransistors, or any suitable device having one or more work functionadjustment material (WFM) layers in the gate structure.

In FET structures, forming multiple devices with different thresholdvoltages (Vt), the composition and dimensions of metal gate layers playa crucial role in defining the Vt. Multiple FETs having differentthreshold voltages can be realized by adjusting materials and/ordimensions of one or more work function adjustment material (WFM) layersdisposed between a gate dielectric layer and a body metal gate electrodelayer (e.g., a W layer). If there is insufficient control of thephotolithographic operations, the dimensions of the metal gate layersmay not be consistent, which affects its work function and therebyaffects threshold voltage and degrades device performance.

In the following embodiment, methods of providing WFM layers withconsistent and controlled dimensions are discussed.

FIG. 18 shows a cross section view of gate structures for FETs withdifferent threshold voltages according to an embodiment of the presentdisclosure. In some embodiments, a semiconductor device includes a firstn-type FET N1, a second n-type FET N2, a third n-type FET N3, a firstp-type FET P1, a second p-type FET P2 and a third p-type FET P3. Athreshold voltage of the first n-type FET N1 is smaller in an absolutevalue than a threshold voltage of the second n-type FET N2 and thethreshold voltage of the second n-type FET N2 is smaller in an absolutevalue than a threshold voltage of the third n-type FET N3. Similarly, athreshold voltage of the first n-type FET P1 is smaller in an absolutevalue than a threshold voltage of the second p-type FET P2 and thethreshold voltage of the second p-type FET P2 is smaller in an absolutevalue than a threshold voltage of the third p-type FET P3.

FIGS. 19A-19R show cross sectional views of various stages ofmanufacturing the semiconductor device shown in FIG. 18 , according toembodiments of the present disclosure. It is understood that in thesequential manufacturing process, one or more additional operations canbe provided before, during, and after the stages shown FIGS. 190A-19Rand some of the operations described below can be replaced or eliminatedfor additional embodiments of the method. The order of theoperations/processes may be interchangeable. Accordingly, one or moreoperations as shown in FIGS. 19A-19R may be omitted or replaced withanother operation depending on the structure of the semiconductordevice.

FIG. 19A illustrates a plurality of channel regions of a first n-typeFET N1, a second n-type FET N2, a third n-type FET N3, a first p-typeFET P1, a second p-type FET P2 and a third p-type FET P3, respectively.An interfacial layer 210 is formed over each of the channel regions. Agate dielectric layer (e.g., a high-k gate dielectric layer) 230 isformed over each of the interfacial layers 210. A first conductivelayer, as a cap layer 235, is formed over each of the gate dielectriclayers 230.

In some embodiments, the interfacial layer 210 is formed by usingchemical oxidation. In some embodiments, the interfacial layer 210includes one of silicon oxide, silicon nitride and mixedsilicon-germanium oxide. The thickness of the interfacial layer 210 isin a range from about 0.2 nm to about 6 nm in some embodiments. In someembodiments, the gate dielectric layer 230 includes one or more layersof a dielectric material, such as silicon oxide, silicon nitride, or ahigh-k dielectric material, other suitable dielectric material, and/orcombinations thereof. Examples of high-k dielectric materials includeHfO₂, HfSiO, HfSiON, HfTaO, HfSiO, HfZrO, zirconium oxide, aluminumoxide, titanium oxide, hafnium dioxide-alumina (HfO₂—Al₂O₃) alloy,La₂O₃, HfO₂—La₂O₃, Y₂O₃ or other suitable high-k dielectric materials,and/or combinations thereof. The gate dielectric layer 230 may be formedby CVD, ALD or any suitable method. In one embodiment, the gatedielectric layer 230 is formed using a highly conformal depositionprocess such as ALD in order to ensure the formation of a gatedielectric layer having a uniform thickness around each channel layer.The thickness of the gate dielectric layer 230 is in a range from about1 nm to about 100 nm in some embodiments. In some embodiments, the firstconductive layer 235 is a TiN or TiSiN layer formed by CVD, ALD or anysuitable method.

In some embodiments, a second conductive layer, as a first barrier layer245, is formed on the cap layer 235, as shown in FIG. 19B. In someembodiments, the cap layer 235 is removed after an annealing operationand the first barrier layer 245 is not formed. In some embodiments, thesecond conductive layer 245 includes a metal nitride, such as WN, TaN,TiN and TiSiN. In some embodiments, TaN is used. The thickness of thesecond conductive layer 245 is in a range from about 0.3 nm to about 30nm in some embodiments, and is in a range from about 0.5 nm to about 25nm in other embodiments. In some embodiments, the second conductivelayer 245 functions as a barrier layer or an etch stop layer. In someembodiments, the second conductive layer 245 is thinner than the firstconductive layer 235.

As shown in FIG. 19C, a WFM layer 200 is formed in some embodiments. Insome embodiments, the WFM layer 200 is an n-type WFM layer. In someembodiments, the WFM layer is made of a conductive material such as asingle layer of TiN, WN, TaAlC, TiC, TaAl, TaC, Co, Al, TiAl, or TiAlC,or a multilayer of two or more of these materials. For an n-type FET, analuminum containing layer, such as TiAl, TiAlC, TaAl and/or TaAlC isused as an n-type WFM layer 200, and for a p-type FET, one or more ofTaN, TiN, WN, TiC, WCN, MoN and/or Co is used as a p-type WFM layer insome embodiments. In some embodiments, an n-type WFM layer is composedof materials having a low work function in a range from about 2.5 eV toabout 4.4 eV and/or having low electronegativity. In some embodiments, ap-type WFM layer is composed of materials having a high work function ina range from about 4.3 eV to 5.8 eV and/or having highelectronegativity. In some embodiments, a thickness of the n-type WFMlayer 200 is in a range from about 0.6 nm to about 40 nm, and is in arange from about 1 nm to about 20 nm in other embodiments.

A first patterning operation is performed to remove the n-type WFM layer200 from the regions for the first p-type FET P1, the second p-type FETP2 and the third p-type FET P3. In some embodiments, a bottom layer 260made of the bottom layer compositions disclosed herein with reference toFIGS. 11-14C is formed over each of the n-type WFM layers 200. A middlelayer 300 made according to the embodiments disclosed herein (e.g.,FIGS. 3 and 15A-16B) is formed over each of the bottom layers 260, and aphotoresist layer 205 made of any of the photoresist compositiondisclosed herein is formed over the each of the middle layers 300, asshown in FIG. 19D. By using one or more lithography operations, thephotoresist layer 205 is patterned to expose the middle layers 300 atthe regions for the p-type FETs. Then, the exposed middle layer 300 andbottom layer 260 are removed by one or more etching operations, toexpose the n-type WFM layers 200 at the regions for the p-type FETs, asshown in FIG. 19E. A plasma etching operation utilizes a gas includingN₂ and H₂, a gas including O₂/Cl₂, or O₂ gas in some embodiments

Subsequently, the n-type WFM layer 200 in the regions for the p-typeFETs are removed by an appropriate etching operation, as shown in FIG.19F. In some embodiments, the etching operation includes a wet etchingoperation. The etching solution (etchant) includes an aqueous solutionof HCl and H₂O₂, an aqueous solution of the combination of NH₄OH andH₂O₂, an aqueous solution of the combination of HCl, NH₄OH and H₂O₂, anaqueous solution of HF, NH₄OH and H₂O₂ and/or an aqueous solution ofH₃PO₄ and H₂O₂ in some embodiments. The wet etching substantially stopsat the first barrier layer 245, which thus functions as an etch stoplayer. In some embodiments, the gate dielectric layer 230 acts as anetch stop layer instead of first barrier layer.

After the wet etching operation, a wet cleaning operation or a deionizedwater rinsing is performed in some embodiments. The photoresist layer205, middle layer 300, and the bottom layer 260 are removed aresubsequently removed from the n-type FET regions, as shown in FIG. 19G.In some embodiments, a plasma ashing operation using an oxygencontaining gas is performed to remove the organic photoresist layer 205,middle layer, and the bottom layer 200. In some embodiments, an N₂/H₂based plasma or a CF₄ based plasma is used for the plasma ashingoperation.

In some embodiments, a third conductive layer, as a second barrier layer250, is formed over the n-type WFAM layers 200 for the n-type FETs andover the first barrier layer 245 at the regions for the p-type FETs, asshown in FIG. 19H. A blanket layer of the second barrier layer 250 isformed over the regions of the n-type and p-type FETs in someembodiments. In some embodiments, TaN is used as the third conductivelayer 250. The thickness of the third conductive layer 250 is in a rangefrom about 0.3 nm to about 30 nm in some embodiments, and is in a rangefrom about 0.5 nm to about 25 nm in other embodiments.

A blanket layer of a first p-type WFM layer 280 is formed over each ofthe second barrier layers 250 at the regions for the n-type and p-typeFETs, as shown in FIG. 19I. In some embodiments, a thickness of thefirst p-type WFM layers 280 is in a range from about 0.5 nm to about 20nm, and is in a range from about 1 nm to about 10 nm in otherembodiments.

Next, a second patterning operation is performed to remove the firstp-type WFM layer 280 from the regions for the first and second n-typeFETs N1, N2 and the second and third p-type FETs P2, P3. A second bottomlayer 265 made of the bottom layer compositions disclosed herein isformed over each of the first p-type WFM layers 280. A second middlelayer 305 made of the middle layer compositions disclosed herein isformed over each of the second bottom layers, and a second photoresistlayer 215 formed of any of the photoresist compositions disclosed hereinis formed over the second middle layer 305, as shown in FIG. 19J. Byusing one or more lithography operations, the second photoresist layer215 is patterned to expose the second middle layer 305 at the regionsfor the first and second n-type FETs N1, N2 and second and third p-typeFETs P2, P3. Then, the exposed middle layer 305 and the second bottomlayer 265 are removed by one or more plasma etching operations, toexpose the first p-type WFM layer 280 at the regions for the first andsecond n-type FETs N1, N2 and second and third p-type FETs P2, P3, asshown in FIG. 19K. The plasma etching utilizes a gas including N₂ andH₂, a gas including O₂/Cl₂, or O₂ gas.

Subsequently, the first p-type WFM layer 280 in the regions for thefirst and second n-type FETs N1, N2 and second and third p-type FETs P2,P3 is removed by an appropriate etching operation, as shown in FIG. 19L.In some embodiments, the etching operation includes a wet etchingoperation. The etching solution (etchant) includes an aqueous solutionof H₃PO₄ and H₂O₂, an aqueous solution of the combination of HCl, NH₄OHand H₂O₂ in some embodiments. The wet etching substantially stops at thesecond barrier layer 250, which thus functions as an etch stop layer.

After the wet etching operation, a wet cleaning operation or a deionizedwater rinsing is performed in some embodiments. The second photoresistlayer 215, second middle layer 305, and the second bottom layer 265 aresubsequently removed as shown in FIG. 19M. In some embodiments, a plasmaashing operation using an oxygen containing gas is performed to removethe organic second photoresist layer 215, second middle layer, andsecond bottom layer 265. In some embodiments, an N₂/H₂ based plasma or aCF₄ based plasma is used for the plasma ashing operation.

A blanket layer of a second p-type WFM layer 285 is formed over thesecond barrier layer 250 at the regions for the first and second n-typeFETs N1, N2 and the second and third p-type FETs P2, P3 and over thefirst p-type WFM layer 280 at the regions for the third n-type FET N3and the first p-type FET P1 in some embodiments, as shown in FIG. 19N.In some embodiments, a thickness of the second p-type WFM layers 285 isin a range from about 0.5 nm to about 20 nm, and is in a range fromabout 1 nm to about 10 nm in other embodiments.

A third patterning operation subsequently is performed to remove thesecond p-type WFM layer 285 from the regions for the first n-type FET N1and the third p-type FET P3. In some embodiments, a third bottom layer270 made of the bottom layer compositions disclosed herein is formedover the second p-type WFM layer 285, a third middle layer 310 made ofany of the middle layer compositions disclosed herein, and a thirdphotoresist layer 225 made of any of the photoresist compositionsdisclosed herein are formed over the third bottom layer 270, as shown inFIG. 19O. By using one or more lithography operations, the thirdphotoresist layer 225 is patterned, to expose the third middle layer 310at the regions for the first n-type FET N1 and the third p-type FET P3.Then, the exposed third middle layer 310 and the third bottom layer 270are removed by one or more plasma etching operations, to expose thesecond p-type WFM layer 285 at the regions for the first n-type FET N1and the third p-type FET P3, as shown in FIG. 19P. The plasma etchingutilizes a gas including N₂ and H₂, a gas including 02/C12, or 02 gas.

Subsequently, the second p-type WFM layer 285 in the regions for thefirst n-type FET N1 and the third p-type FET P3 is removed by anappropriate etching operation, as shown in FIG. 19Q. In someembodiments, the etching operation includes a wet etching operation. Theetching solution (etchant) includes an aqueous solution of H₃PO₄ andH₂O₂, an aqueous solution of the combination of HCl, NH₄OH, and H₂O₂ insome embodiments. The wet etching substantially stops at the secondbarrier layer 250, which thus functions as an etch stop layer.

After the wet etching operation, a wet cleaning operation or a deionizedwater rinsing is performed in some embodiments. The third photoresistlayer 225, the third middle layer 310, and the third bottom layer 270are subsequently removed as shown in FIG. 19R. In some embodiments, aplasma ashing operation using an oxygen containing gas is performed toremove the third photoresist layer 225, third middle layer 310, and thebottom layer 270. In some embodiments, an N₂/H₂ based plasma or a CF₄based plasma is used for the plasma ashing operation.

A glue layer 290 is subsequently formed over the second barrier layer250 at the regions for the first n-type FET N1 and the third p-type FETP3, over the second p-type WFM layer 285 at the regions for the secondand third n-type FETs N2, N3 and the first and second p-type FETs P1,P2, and a body gate electrode layer 295 is formed over glue layer 290 insome embodiments to provide the semiconductor device shown in FIG. 18 .

In some embodiments, the glue layer 290 is made of TiN, Ti, or Co. Insome embodiments, the body gate electrode layer 295 includes one or morelayers of conductive material, such as polysilicon, aluminum, copper,titanium, tantalum, tungsten, cobalt, molybdenum, tantalum nitride,nickel silicide, cobalt silicide, TiN, WN, TiAl, TiAlN, TaCN, TaC,TaSiN, metal alloys, other suitable materials, and/or combinationsthereof.

Other embodiments include other operations before, during, or after theoperations described above. In some embodiments, the disclosed methodsinclude forming semiconductor devices, including fin field effecttransistor (FinFET) structures. In some embodiments, a plurality ofactive fins are formed on the semiconductor substrate. Such embodiments,further include etching the substrate through the openings of apatterned hard mask to form trenches in the substrate; filling thetrenches with a dielectric material; performing a chemical mechanicalpolishing (CMP) process to form shallow trench isolation (STI) features;and epitaxy growing or recessing the STI features to form fin-likeactive regions. In some embodiments, one or more gate electrodes areformed on the substrate. Some embodiments include forming gate spacers,doped source/drain regions, contacts for gate/source/drain features,etc. In other embodiments, a target pattern is formed as metal lines ina multilayer interconnection structure. For example, the metal lines maybe formed in an inter-layer dielectric (ILD) layer of the substrate,which has been etched to form a plurality of trenches. The trenches maybe filled with a conductive material, such as a metal; and theconductive material may be polished using a process such as chemicalmechanical planarization (CMP) to expose the patterned ILD layer,thereby forming the metal lines in the ILD layer. The above arenon-limiting examples of devices/structures that can be made and/orimproved using the method described herein.

In some embodiments, active components such diodes, field-effecttransistors (FETs), metal-oxide semiconductor field effect transistors(MOSFET), complementary metal-oxide semiconductor (CMOS) transistors,bipolar transistors, high voltage transistors, high frequencytransistors, FinFETs, other three-dimensional (3D) FETs, other memorycells, and combinations thereof are formed, according to embodiments ofthe disclosure.

The novel middle layer compositions and semiconductor devicemanufacturing methods according to the present disclosure provide highersemiconductor device feature yield. Embodiments of the presentdisclosure include methods and materials that reduce scum defects,thereby improving pattern resolution, decreasing line width roughness,decreasing line edge roughness, and improving semiconductor deviceyield. Embodiments of the disclosure further enables the use of lowerexposure doses to effectively expose and pattern the photoresist.

An embodiment of the disclosure is a method of manufacturing asemiconductor device including forming a first layer including anorganic material over a substrate. A second layer including a reactionproduct of a silicon-containing material and a photoacid generator isformed over the first layer. A photosensitive layer is formed over thesecond layer, and the second layer is patterned. In an embodiment, thesilicon-containing material is a siloxane or a spin-on-glass. In anembodiment, the photoacid generator includes a sulfonium cation. In anembodiment, the photoacid generator includes a triphenyl sulfoniumcation. In an embodiment, the forming the second layer includes:applying a mixture including the reaction product of thesilicon-containing material and the photoacid generator over the firstlayer; and heating the mixture to polymerize or crosslink the reactionproduct of the photoacid generator and the silicon-containing materialafter applying the mixture over the first layer. In an embodiment, themixture is heated at a temperature ranging from 150° C. to 300° C. In anembodiment, the patterning the photosensitive layer includes:patternwise exposing the photosensitive layer to actinic radiation,heating the patternwise exposed photosensitive layer and the secondlayer at a temperature ranging from 80° C. to 160° C., and developingthe photosensitive layer after the heating. In an embodiment, thephotoacid generator includes a sulfonium cation and a sulfite anion.

Another embodiment of the disclosure is a method of manufacturing asemiconductor device, including forming a bottom anti-reflective coatinglayer over a substrate. A middle layer including a silicon-containingpolymer with pendant photoacid generator groups is formed over thebottom anti-reflective coating layer. A photosensitive layer is formedover the middle layer. The photosensitive layer is selectively exposedto actinic radiation to form a latent pattern, and the photosensitivelayer is selectively exposed to form a pattern in the photosensitivelayer. In an embodiment, the silicon-containing polymer is apolysiloxane. In an embodiment, the photoacid generator groups include asulfonium cation and a sulfite anion. In an embodiment, thephotosensitive layer includes a polymer having pendant acid labilegroups and a photoacid generator compound. In an embodiment, an anion ora cation of the photoacid generator compound is different from an anionor a cation of the pendant photoacid generator groups. In an embodiment,the method includes heating the selectively exposed photosensitive layerat a temperature ranging from 80° C. to 160° C. before the developingthe selectively exposed photosensitive layer.

Another embodiment of the disclosure is a method of manufacturing asemiconductor device, including forming a bottom layer of a trilayerresist over a substrate and forming a middle layer of a trilayer resistover the bottom layer. The middle layer includes a silicon-containingmaterial with pendant photoacid generator groups. A photosensitive layeris formed over the middle layer. The photosensitive layer and the middlelayer are selectively exposed to actinic radiation. Acid released by thependant photoacid generator groups in exposed portions of the middlelayer is diffused into exposed portions of the photosensitive layer. Adeveloper composition is applied to the selectively exposedphotosensitive layer to form a pattern in the photosensitive layer. Inan embodiment, the silicon-containing material is a polysiloxane or acured spin-on-glass. In an embodiment, the diffusing acid released bythe pendant photoacid generator groups in exposed portions of the middlelayer into exposed portions of the photosensitive layer includes heatingthe photosensitive layer and the middle layer at a temperature rangingfrom 80° C. to 160° C. before the applying the developer. In anembodiment, forming the middle layer includes heating the middle layerat a temperature ranging from 150° C. to 300° C. to polymerize orcrosslink the silicon-containing material with pendant photoacidgenerator groups. In an embodiment, the photosensitive layer includes apolymer having pendant acid labile groups and a photoacid generatorcompound. In an embodiment, an anion or a cation of the photoacidgenerator compound is different from an anion or a cation of the pendantphotoacid generator groups.

The foregoing outlines features of several embodiments or examples sothat those skilled in the art may better understand the aspects of thepresent disclosure. Those skilled in the art should appreciate that theymay readily use the present disclosure as a basis for designing ormodifying other processes and structures for carrying out the samepurposes and/or achieving the same advantages of the embodiments orexamples introduced herein. Those skilled in the art should also realizethat such equivalent constructions do not depart from the spirit andscope of the present disclosure, and that they may make various changes,substitutions, and alterations herein without departing from the spiritand scope of the present disclosure.

What is claimed is:
 1. A method of manufacturing a semiconductor device,comprising: forming a first layer comprising an organic material over asubstrate; forming a second layer comprising a reaction product of asilicon-containing material and a photoacid generator over the firstlayer; forming a photosensitive layer over the second layer; andpatterning the photosensitive layer.
 2. The method according to claim 1,wherein the silicon-containing material is a siloxane or aspin-on-glass.
 3. The method according to claim 1, wherein the photoacidgenerator includes a sulfonium cation.
 4. The method according to claim1, wherein photoacid generator includes a triphenyl sulfonium cation. 5.The method according to claim 1, wherein the forming the second layercomprises: applying a mixture comprising the reaction product of thesilicon-containing material and the photoacid generator over the firstlayer; and heating the mixture to polymerize or crosslink the reactionproduct of the photoacid generator and the silicon-containing materialafter applying the mixture over the first layer.
 6. The method accordingto claim 5, wherein the mixture is heated at a temperature ranging from150° C. to 300° C.
 7. The method according to claim 1, wherein thepatterning the photosensitive layer comprises: patternwise exposing thephotosensitive layer to actinic radiation; heating the patternwiseexposed photosensitive layer and the second layer at a temperatureranging from 80° C. to 160° C.; and developing the photosensitive layerafter the heating.
 8. The method according to claim 1, wherein thephotoacid generator includes a sulfonium cation and a sulfite anion. 9.A method of manufacturing a semiconductor device, comprising: forming abottom anti-reflective coating layer over a substrate; forming a middlelayer comprising a silicon-containing polymer with pendant photoacidgenerator groups over the bottom anti-reflective coating layer; forminga photosensitive layer over the middle layer; selectively exposing thephotosensitive layer to actinic radiation to form a latent pattern; anddeveloping the selectively exposed photosensitive layer to form apattern in the photosensitive layer.
 10. The method according to claim9, wherein the silicon-containing polymer is a polysiloxane.
 11. Themethod according to claim 9, wherein the photoacid generator groupsinclude a sulfonium cation and a sulfite anion.
 12. The method accordingto claim 9, wherein the photosensitive layer comprises a polymer havingpendant acid labile groups and a photoacid generator compound.
 13. Themethod according to claim 12, wherein an anion or a cation of thephotoacid generator compound is different from an anion or a cation ofthe pendant photoacid generator groups.
 14. The method according toclaim 9, further comprising heating the selectively exposedphotosensitive layer at a temperature ranging from 80° C. to 160° C.before the developing the selectively exposed photosensitive layer. 15.A method of manufacturing a semiconductor device, comprising: forming abottom layer of a trilayer resist over a substrate; forming a middlelayer of a trilayer resist over the bottom layer, wherein the middlelayer comprises a silicon-containing material with pendant photoacidgenerator groups; forming a photosensitive layer over the middle layer;selectively exposing the photosensitive layer and the middle layer toactinic radiation; diffusing acid released by the pendant photoacidgenerator groups in exposed portions of the middle layer into exposedportions of the photosensitive layer; and applying a developercomposition to the selectively exposed photosensitive layer to form apattern in the photosensitive layer.
 16. The method according to claim15, wherein the silicon-containing material is a polysiloxane or a curedspin-on-glass.
 17. The method according to claim 15, wherein thediffusing acid released by the pendant photoacid generator groups inexposed portions of the middle layer into exposed portions of thephotosensitive layer comprises heating the photosensitive layer and themiddle layer at a temperature ranging from 80° C. to 160° C. before theapplying the developer.
 18. The method according to claim 15, whereinthe forming the middle layer comprises heating the middle layer at atemperature ranging from 150° C. to 300° C. to polymerize or crosslinkthe silicon-containing material with pendant photoacid generator groups.19. The method according to claim 18, wherein the photosensitive layercomprises a polymer having pendant acid labile groups and a photoacidgenerator compound.
 20. The method according to claim 19, wherein ananion or a cation of the photoacid generator compound is different froman anion or a cation of the pendant photoacid generator groups.